She enlisted the help of Viners-turned-rappers Jack & Jack to chime in on a stand-out guest verse, and she wisely tapped them to star in her music video, too.

Written by her big brother and Selena Gomez — dream team, right?

— Alli snagged soon-to-be pop anthem "Roll ' Em Up" for herself.

His caption thrilled, “So I see @justinbieber and @codysimpson jammed last night in la.

Good stuff.” Braun’s clip and another snippet of the same track were later uploaded to You Tube by a fan account.

” while trying to prevent her from getting into a waiting car with the others.

An eyewitness tweeted that the guard then realized his mistake and apologetically told her “Oh no, my bad my bad.” To which the model apparently responded by laughing.

Justin Bieber and Cody Simpson surprised patrons at The Nice Guy in West Hollywood on Monday night, when they performed an acoustic set which included their 2014 duet “Home To Mama.” The Canadian superstar also sang Tracy Chapman’s 1988 classic “Fast Car” and Edwin Mc Cain’s 1998 hit “I’ll be” with Cody providing accompaniment on guitar during their 30-minute show.

The “Where Are U Now” singer was also seen in a Snapchat story filmed in a vehicle and posted by Madison, during which he asked the girls if he should wear a pair of socks that he called “toe shoes.” “The shoes,” Baldwin wrote alongside a snap of Bieber and the aforementioned socks.At the end of the night when Justin left the venue with Hailey and Madison in tow, one club security guard mistook Baldwin for a fan and loudly asked her, “What are you doing!Social media posts shared by the 18-year-old Topshop model and Beer revealed Madison also sang at one point and was seen larking about with Justin, while Hailey shared a shot of the heartthrob to her Instagram.Bieber and Beer’s manager, Scooter Braun also got in on the online action and posted an Instagram video of the “Home To Mama” performance.Alli Simpson — the 17-year-old host on Radio Disney, face of Mudd, and little sister to Cody — is hard at work on a music career when she's not busy doing one of the million other things occupying her schedule.

Though she's had a string of catchy pop singles, her latest track is hands-down her most impressive yet.